Contact member stock comprising a strip of electrically conductive metal and bonded thereto a sequence of spaced malleable metal balls adapted to be flattened



Sept. 27, 1

A. J. THOMSON ET AL 3,275,425 CONTACT MEMBER STOCK COMPRISING A STRIP OF ELECTRICAL DUCTIVE METAL AND BONDED THERETO A SEQUENCE OF SPA V MALLEABLE METAL BALLS ADAP'IED TO BE FL E Original Filed Sept. 1

, i961 shee Sheet 1 Sept. 27, 1966 THOMSON ET AL 3,275,425

CONTACT MEMBER STOCK COMPRISING A STRIP OF ELECTRICALIJY CONDUCTIVE METAL AND BONDED THEREI'O A SEQUENCE OF SPACED MALLEABLE METAL BALLS ADAPTED TO'BE FLATTENED Original Filed Sept. 1, 1961 2 Sheets-Sheet 2 United States Patent Office 3,275,425 Patented Sept. 27, 1966 CONTACT lVIElVIBER STOCK COMPRISING A STRIP OF ELECTRICALLY CONDUCTIVE METAL AND BONDED THERETO A SEQUENCE OF SPACE!) MALLEABLE METAL BALLS ADAPTED TO BE FLATTENED Arthur James Thomson, Oakland, R.I., and Gerard R. Achiu, North Attleboro, and Frank Rynhart, Taunton, Mass., assignors to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Original application Sept. 1, 1961, Ser. No. 135,636, now Patent No. 3,194,940, dated July 13, 1965. Divided and this application Jan. 15, 1964, Ser. No. 337,949

10 Claims. (Cl. 29-1835) This is a division of application Serial No. 135,636, filed September 1, 1961, now Patent No. 3,194,940.

This invent-ion relates to contact member stock, and more particularly to stock of this character in the nature of an intermediate pro-duct for use in producing electrical contacts.

Among the several objects of the invention may be noted the provision of stock such as described which is adapted for conversion to miniaturized electrical contacts. In general, as will appear, the stock of this invention comprises a strip of metal having a row or sequence of spaced metal balls welded thereto. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the constructions hereinafter described, and the scope of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated.

FIG. 1 is an end elevation of apparatus for producing stock of this invention;

FIG. 2 is a jogged horizontal section taken on line 2-2 of FIGS. 1 and 3;

FIG. 3 is a jogged vertical section taken on line 3--3 of FIG. 2, parts being additionally broken away, certain reciprocating parts being in retracted positions;

FIG. 4 is a fragmentary view of right-hand parts of FIG. 3, showing alternateadvanced positions of parts;

FIG. 5 is an enlarged plan view of one form of an intermediate contact strip product that may be made according to the invention;

FIG. 6 is an enlarged fragmentary cross section taken on line 6--6 of FIG. 4; and

FIG. 7 is an enlarged cross section taken on line 7-7 of FIG. 5, being enlarged on the scale of FIG. 6.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

The reliable placement and attachment of electrical contacts, such as of gold, silver or the like, to conductive contact members for electrical apparatus, particularly when high accuracies are required in making miniaturized devices generally involves slow, cumbersome and costly operations many times resulting in low yields. This is because of the finicky nature of the operations necessary, particularly when operating with small parts. We have discovered that placements and attachments of this nature can be made rapidly, accurately and economically by welding small balls or spheres of gold, silver or the like malleable material on conductive strip material, thereby form ing an intermediate product comprising the strip with the metal balls welded thereto a-t spaced intervals, and subsequently performing a coining operation on the welded balls on the strip material to provide a desired finished contact form, e.g. a semilenticula'r form.

:By way of example but without limitation, the case will be considered herein wherein gold spheres or balls of approximately .023 inch in diameter are to be welded to a continuous strip of electrically conductive stock at a predetermined distance apart. The stock is rectangular in section, .020 inch thick and .062 inch wide. The invention is particularly useful for assembling such small-scale parts.

Referring now more particularly to the drawings, there is shown at numeral 1 a fixed bed having openings 3 therein in which are located upwardly extending electrodes 5, composed for example of thoriated tungsten. On the bed 1 is a channel-shaped electrically insulated cradle 7 for holding in position a conductive bus bar 9, through which the electrodes 5 extend and to which they are attached so as to become fixed and to receive current therefrom. At numeral 11 is shown a conductive rod extending from the bus bar 9 for making a connection to a suitable supply of welding current.

Extending up from the bed 1 are four guide posts 13 for guiding a vertically movable guide platen 1'5 composed of electrically insulating material. Platen 15 carries attached bushings 1'7 slidable on the posts 13. Adjustable heads 19, engageable by bushings 17, determine the upper limit of the motion of the platen .15. Springs 21 around posts 13 under bushings 17 bias the platen 15 upward to its upper limit.

Attached to and depending from the platen 15 is a ball holder 23, also composed of insulating material. This holder forms three round bowls, sockets or cups 25, having bottoms converging conically to openings 27 through which are slidably accepted the fixed electrodes 5. The diameters of the openings 27 are such that the holder 23 of platen 1-5 slides or telescopes freely on the electrodes 5 with small clearance. Each electrode is formed at its upper end as a cone 29, terminating in a hemispherical socket 31 adapted to nest a single ball of the size to be welded, such as shown for example at B. A supply of balls such as B is maintained in each bowl 25, being introduced through feed ports 33 extending through the platen 15. Balls may be removed when desired through outlet ports 36 in holder 23. Ports 36 are normally closed by screw caps 38.

The bottom of the platen 15 and the toptof the container 23 are shaped to form a slot establishing collinear guide passages 35 of proper cross section for accepting and guiding a strip such as 37. Strip 37 is composed of prepunched conductive clip-forming material of indefinite length (FIG. 5), generally supplied from a reel. The collineating axis of passages 35 diametrically crosses the centers of bowls 25 and establishes a pass line P-L. At these centers are holes 39 in which are relatively slidable electrodes 41. The lower ends of the electrodes 41 are engageable with strip material 37, extending through the passages 35 and across the tops of the bowls 25.

Each electrode 41 extends from a bushing 43 to which it is attached in electrically insulating relationship. Each bushing 43 has a collar 45 at its lower end and an adjustable head 47 on its upper end constituted by threaded lock nuts as shown. Each bushing 43 is slidable in an opening 49 in a reciprocating crosshead 51. Each bush: ing 43, carryingitsrespective electrode 41, is biased downward by a spring 53 until its stop head 47 engages the crosshead 51.1 The crosshead 51 is preferably composed of non-magnetic material. In FIG. 3 itis in its uppermost I position.

Extending down from oppositeends of the crosshead 51 are adjustable. drive pins 55, the lower ends of which have a small clearance 'vw'th respect to the platen 15 when the crosshead 51 is retracted upward as far as it will go (see FIGS. 1 and 3). Under these conditions the lower ends of the electrodes41 in a first position (FIG. 3) are slightly above the top side of a strip 37 located in the passages 35, the amount being slightly less than said clearance.

double-acting piston 70, connected with the crosshead 51 1 through apiston rod 71 and a forked connection 73. Through conventional means, the piston may be pneumatically driven up and down for predetermined distances which establish the upper and lower limits of movement of the crosshead 51.

On one end of the platen 15 (FIG. 3, left side), is located a guide block 79, containing a passage 75 for accepting the strip 37. It also contains a cross passage 81 for registering with a holding pin 83, fixedly supported on the bed 1 by means indicated at 85. The'block 79 reciprocates relative to the pin 83 as the platen 15 reciprocates. The strip 37 is provided at intervals with register openings 87 corresponding to the' pitch distance desired between locations of contact balls B, to be placed thereon.

It will be clear from the above that each movableelec- V trode 41 is coaxial with one of the fixed electrodes 5, so

To the right of the apparatus (as viewed in FIG. 3)

is located a conventional hitch feed device 40 by means of which the strip 37 is intermittently gripped and drawn approximately one pitch distance to the right each time the parts assume the position shown in FIG. 3. This feeding arrangement approximately registers succeeding openings 87 with openings 81. Thereafter, the pin 83 enters the opening so as accurately to register it as the platen 15 descends. At this time the pin 81 functions as locating means for the strip 37.

Operation is as follows, assuming that a prepunched strip 37 has been threaded through niembers79, 15 and 23 and approximate registry obtained between one opening 87 and the opening 81, as illustrated in FIG. 3:

Air is admitted above the piston 70 to 'drive down the crosshead 51. This takes up the clearance between the lower ends. of the, drive pins 55 and theplaten 15. also compresses springs 53, as the lower ends of the electrodes 41fcome from a first separated position (FIG-3) to a contacting position (FIG. 4) in good electrical contact with the upper surface of the strip 37 extending across cups 25. Then the platen 15, with the .ball holder 23, descends, compressing the. return springs 21 (see FIG. 4). Pin 83 enters an opening 87. Relative motion occurs between the cups and the lower fixed electrodes 5,

which act as lance-type selector plungers. As these lower electrodes. in a relative sense plunge up through the mass of balls in the cups, one ball only in each case will position itself in the respective electrode socket 31. This is due to the conical shape of each electrode 5 around its socket. .The conical shape also prevents damage to balls as the electrode moves through the mass of the same. Ultimately each ball in a socket 31 will be engaged by that part of the lower side of the strip 37 which is under This . 4 the lower end of the respective contacting electrode 41; As soon as contact is'madebetween each ball B and the strip 37, the exciting circuit connected across terminals 11 l and 63 will be completed and welding current will weld the balls to the strip 37, as schematically illustrated in FIG. 6. Thereafter air is exhausted from above the piston 70 and introduced below it, thus moving the crosshead 51 upward and returning the partsto the FIG. 3

position. vThen the .hitchfeed indexes another pitch length of the strip 37 into proper position across the cups 25 so that the next opening 87 approximately. registers with the center-line of pin 83; As this approximate regis try occurs, the crosshead 51 descends, driving pin 83 into this opening 87, andthe operation is repeated. The passages 35 are deep enough to accommodate exit movements of the ballsB asthe strip to which they are tangentially welded moves out of the apparatus to form a useful j intermediate product. Since the strip came from a reel as above described, it maybe re-reeled,,which .is to say that it is coilable, for convenient shipment ,or handling.

In FIG. 7 is shown how the intermediate product of ribbon form'with the balls B accurately welded in place. is useful. It is subsequently treated by coining each weld-" ed ball, i.e., deforming each ball B by compressing it until it, assumes the flattened semilenticular form shown, to

form a contact welded to the strip 37. Thereafter the.

strip 37 is cut up and formed by suitable operations into terminal clips, each one of which has on it a contact such as shown. at B in FIG. 7. In view of the above, it is' apparent that the strip, carrying the flattened-contacts may be coiled for convenient shipment or handling before being divided.

While three weldments aremade] at a timeby the apt paratus illustrated, due .to the three-component gang arrangement illustrated, a single weldment may be made at a time (see FIG. 5, for example), or as is obvious any. other number desired.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above COB? structions without departing from the scope of the inven t tion, it is intended that all'matter contained in the above description or shown in the accompanying drawings shall be interpreted vas-illustrative and not in a limiting sense.

What is claimed is:

1. The elongate intermediate-electrical, product for.

making electrical terminal contact elements by division therefrom, comprising a strip of-substantially electrically conductive metal stock, and a sequence of spaced malleable .metal balls which are both substantially spherical and electrically conductive, said balls being substantially tangentially electrically welded to the strip.

21A product according to claim. 1, wherein the strip is of right-angular .cross section, each of the two dimensions of which is a few thousandths of an inch, each of said 1 therefrom,'comprising a strip of substantially electrically.

conductive metal stock, and a sequence of spaced malle-.

able electrically conductive substantially 'flattened shapes of conductive metal, eachcoined from spherical electrically conductive malleaable balls which have been electrically welded to the strip.

5. A product according to claim 4, wherein the strip is in the form of a thin coilable ribbon the dimensions of which are on the order of a few thousandths of an inch,

each of said flattened shapes having dimensions on the a order of a few thousandths of an inch and being serniv lenticular in form.

intermediate electrical product for i 6. A product according to claim 5, wherein the ribbon has a sequence of registration openings therethrough.

7. A product according to claim 1, wherein the conductive metal constituting the balls is gold.

8. A product according to claim 1, wherein the conductive metal constituting the balls is silver.

9. A product according to claim 4, wherein the conductive metal of the flattened shapes is gold.

10. A product according to claim 4, wherein the couductive metal of the flattened shapes is silver.

References Cited by the Examiner UNITED STATES PATENTS 2,534,861 12/1950 Foltis 29-190 5 2,692,019 10/ 1954 Zalkind 29193.5

DAVID L. RECK, Primary Examiner.

HYLAND BIZOT, RICHARD DEAN, Examiners. 

1. THE ELONGATE INTERMEDIATE ELECTRICAL PRODUCT FOR MAKING ELECTRICAL TERMINAL CONTACT ELEMENTS BY DIVISION THEREFROM, COMPRISING A STRIP OF SUBSTANTIALLY ELECTRICALLY CONDUCTIVE METAL STOCK, AND A SEQUENCE OF SPACED MALLEABLE METAL BALLS WHICH ARE BOTH SUBSTANTIALLY SPHERICAL AND ELECTRICALLY CONDUCTIVE, SAID BALLS BEING SUBSTANTIALLY TANGETIALLY ELECTRICALLY WELDED TO THE STRIP. 